There is a conventional thermal printer, which is provided with a thermal head at positions corresponding to one side and the other side of thermal paper having a thermosensitive layer on both sides, and prints both sides of thermal paper by operating both thermal heads, or prints one side of thermal paper by operating one of the thermal heads (e.g., Jpn. PAT. Appln. KOKAI Publication No. 2001-71569).
High-sensitive and low-sensitive thermal paper can be set in the above thermal printers.
When high-sensitive thermal paper is set, a print image density may become too high and print quality is degraded. When low-sensitive thermal paper is set, a print image density may become too low and print quality is degraded.
To prevent degradation of print quality, a user is required to check an actually printed image and adjust a print density of a thermal head.
However, such adjustment of print density is very troublesome for the user.